Author Topic: Vintage Leasons Re-learned  (Read 2505 times)

Offline 2qik

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Vintage Leasons Re-learned
« on: February 05, 2011, 09:02:31 PM »
It's been a solid 20 years since I've owned a free-air sled or needed to pre-mix snowmobile gas. 
Here we are in 2011 and my primary ride is a 1974 Cat...

So here's what I've learned:

Riding at temps near 30 degrees doesn't work all that well with old iron.  It's good for about 5 miles on warm days. This thing needs to cool down frequently and it's tough to push much air through the hood with 3 inches of suspension travel...  Probably needs to be on an open lake for warm weather cruising.  Managed to melt (literally) one of the plastic hood vents that sits directly above the pipe.  Fortunately I have a couple spare vents.  I built an aluminum heat shield to prevent this from re-occuring.

I don't think 20:1 pre-mix is necessary with today's oils and fuels.  I'm leaning it down to 40:1 for my next outing.  I think 20:1 has the motor running too lean fuel to air.  Anyone have any insight on modern oil and fuel ratios for vintage sleds?

Otherwise another day of smiles.  Forgot the camera but had a nice ride with my daughter.  We found a quiet patch of woods for a campfire, some sodas and a package of peanut butter cups.  Kids still like sugar...  :banana:

- 2qik
« Last Edit: February 05, 2011, 09:04:05 PM by 2qik »
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Offline Up Late

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Re: Vintage Leasons Re-learned
« Reply #1 on: February 05, 2011, 09:20:55 PM »
Correct on the oil mixture. Newer oils are much better and not diluted like they were in the 1 quart cans of the day. 40-50:1 should be fine unless you are racing, then go 32:1.

Free Airs are interesting, but I never liked the ones I've owned. Good for short runs, but fanners are better if you will be out all day.
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Offline 2qik

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Re: Vintage Leasons Re-learned
« Reply #2 on: February 05, 2011, 10:50:16 PM »
Correct on the oil mixture. Newer oils are much better and not diluted like they were in the 1 quart cans of the day. 40-50:1 should be fine unless you are racing, then go 32:1.

Free Airs are interesting, but I never liked the ones I've owned. Good for short runs, but fanners are better if you will be out all day.

I figured it needed less oil.  Should run cooler @ 40:1.  All day is tough on a 74' w/ 5 gallon gas tank.  They are made for short rides but I wouldn't hesitate to go 50 miles with temps below 20 degrees.  Today I couldn't even see my breath outside which doesn't work for a free-air.  Liquid cooling is the ONLY way to go with temps 30+.

Obviously I won't be enjoying big mile rides with this machine.  What's really cool with an old sled is you don't go as far but you see alot more.  More stops, slower speeds, quality riding.

-2qik
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Offline AdrenalineJunky

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Re: Vintage Leasons Re-learned
« Reply #3 on: February 06, 2011, 08:10:42 PM »
The old sleds like oil.  20:1 adds cushion to those big tolerances unlike what the new stuff is.  Yes today's oil is more refined and can be spread thinner, but 20:1 is how the old stuff is jetted for.  I run 24:1 of synthetic in my free-air jag.  Loves it.  Takes quite a bit to get it hot.  Are your plugs brown?  Sound like you might burn it down.....better check your jetting.
Famous quotes;

Roady; "I just wonder why the big 4 can't produce somnething that remotely ready out of the box"

Myself;  "Even when working properly, the E/S on these cats sounds like a vintage scooby doo lunch box full of hotwheels getting tossed down a flight of concrete stairs."

Offline 2qik

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Re: Vintage Leasons Re-learned
« Reply #4 on: February 08, 2011, 09:28:31 AM »
AJ,

It has number 360 jets in it and that is what the "spec" should be for that year.  Carbs look clean inside including the jets.  Plugs match the NGK application chart.  Plugs read a tan color, I would like to see it more brown, I think it's running on the hot side.

When I gassed it up I took 87 octane I had in the gas can for the snowblower.  I'm now thinking this sled will probably need 91 octane fuel with some octane boost added with compression at 150 psi per side.  The poor fuel is probably contributing to the motor running hotter than I think it should.  Might need to run high grade oil in it also to keep it cooler.  Thoughts?  My last free air was a jag and that sled didn't have the high compression this el tigre has so it wasn't as sensitive to fuel.

I've solved the "fuel starvation" issue with the pump rebuild and a polaris intake pick-up with screen.  It has sucked enough residue into the fuel filter that I needed to replace that within 30 miles.  It now shows 750 miles on the clock so I've done 80 miles of test and tune.

-2qik
Just a typical snowmobiler...

Offline Up Late

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Re: Vintage Leasons Re-learned
« Reply #5 on: February 08, 2011, 09:54:33 AM »
You should to run premium (or mid grade at a minimum) with that compression.
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Offline AdrenalineJunky

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Re: Vintage Leasons Re-learned
« Reply #6 on: February 08, 2011, 10:16:24 AM »
You should to run premium (or mid grade at a minimum) with that compression.
agreed.  Sounds like deto was brigning his temps up.  Just run 93 in it, forget the additive that wont work.  If you really want some good performance out of it...run belray mc-1+ @ one bottle (12.5oz) in 2.5 gals=25:1.   :checkeredflag:
Famous quotes;

Roady; "I just wonder why the big 4 can't produce somnething that remotely ready out of the box"

Myself;  "Even when working properly, the E/S on these cats sounds like a vintage scooby doo lunch box full of hotwheels getting tossed down a flight of concrete stairs."

Offline 2qik

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Re: Vintage Leasons Re-learned
« Reply #7 on: February 08, 2011, 12:58:06 PM »
Is 93 octane easy to find out east?  In northern Minnesota it's rare to have 93 available at trailside pumps.  Since I'm mixing I may get some 110 race gas and mix with 93 or 91 available at the pump.  Fuel quality is much different from when this motor was designed in 71-72 for production in 73-74.

- 2qik
Just a typical snowmobiler...

Offline MELROSEMAFIA

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Re: Vintage Leasons Re-learned
« Reply #8 on: February 10, 2011, 11:20:17 AM »
I put 10's of thousands of miles on those old school free airs back in the day. Most were premixed with straight 30w motor oil, and never had an engine issue if we drove them within the lower specs of the rpm range. Start spinning those engines at 9k and look out. When YAMMI came out with thier injection system back around 69-70, everyone else was still in the stone age. CAT did'nt introduce injection on to their sleds till 1986...lol...BTW... Im currently doing a resto on an 83 Yammi V-Max...Non ethanol 93 premixed at 40:1 (klotz) has worked so far......
« Last Edit: February 10, 2011, 11:46:11 AM by MELROSEMAFIA »

Offline AdrenalineJunky

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Re: Vintage Leasons Re-learned
« Reply #9 on: February 10, 2011, 11:55:04 AM »
I put 10's of thousands of miles on those old school free airs back in the day. Most were premixed with straight 30w motor oil, and never had an engine issue if we drove them within the lower specs of the rpm range. Start spinning those engines at 9k and look out. When YAMMI came out with thier injection system back around 69-70, everyone else was still in the stone age. CAT did'nt introduce injection on to their sleds till 1986...lol...BTW... Im currently doing a resto on an 83 Yammi V-Max...Non ethanol 93 premixed at 40:1 (klotz) has worked so far......
FYI, Oil injection was available on Cat for 79 MY.  Yamaha sleds were junk compared to Cat thruought the 70's early 80's regardless.  Seems you have a early yamie fetish.  Now I know why you claim the 6000 tigers could not hang with yam. lol.
Dont forget the wonderful and famous yam reliability of the 81 srx.   :rolleyes:

BTW, your 83 v-max has less rear susp than a 72 elan with bogies.   :nana:

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« Last Edit: February 10, 2011, 11:59:50 AM by AdrenalineJunky »
Famous quotes;

Roady; "I just wonder why the big 4 can't produce somnething that remotely ready out of the box"

Myself;  "Even when working properly, the E/S on these cats sounds like a vintage scooby doo lunch box full of hotwheels getting tossed down a flight of concrete stairs."

Offline MELROSEMAFIA

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Re: Vintage Leasons Re-learned
« Reply #10 on: February 10, 2011, 02:51:58 PM »
I put 10's of thousands of miles on those old school free airs back in the day. Most were premixed with straight 30w motor oil, and never had an engine issue if we drove them within the lower specs of the rpm range. Start spinning those engines at 9k and look out. When YAMMI came out with thier injection system back around 69-70, everyone else was still in the stone age. CAT did'nt introduce injection on to their sleds till 1986...lol...BTW... Im currently doing a resto on an 83 Yammi V-Max...Non ethanol 93 premixed at 40:1 (klotz) has worked so far......
FYI, Oil injection was available on Cat for 79 MY.  Yamaha sleds were junk compared to Cat thruought the 70's early 80's regardless.  Seems you have a early yamie fetish.  Now I know why you claim the 6000 tigers could not hang with yam. lol.
Dont forget the wonderful and famous yam reliability of the 81 srx.   :rolleyes:

BTW, your 83 v-max has less rear susp than a 72 elan with bogies.   :nana:

El Tigre"s didnt get Injection till 86....Only 17 years behind the times...They also finally caught up to the performance of the other manufacturers in 1986, after getting spanked regularly because the 529 was a dog till they twin piped it...... :checkeredflag:
« Last Edit: February 10, 2011, 02:55:51 PM by MELROSEMAFIA »

Offline 2qik

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Re: Vintage Leasons Re-learned
« Reply #11 on: February 10, 2011, 03:32:00 PM »
I don't see a Yamaha winning a single I-500. 

The 1974 El Tigre won the I-500 and was very competitve 1974 race season.

PAST I-500 CHAMPIONS
WINNIPEG TO ST. PAUL I-500
1966 Herb Howe Polaris
1967 Gerry Reese Polaris
1968 Dale Cormican Arctic Cat
1969 Dale Cormican Arctic Cat
1970 LeRoy Lindblad Polaris
1971 LeRoy Lindblad Polaris
1972 Yvon DuHamel Ski-Doo
1973 Stan Hays Polaris
1974 Marv Ode Arctic Cat
1975 Ed Monsrud Polaris
1976 Brian Nelson John Deere
1977 Archie Simonson Polaris
1978 Brian Nelson Arctic Cat
1979 Paul Matejka Polaris
1980 Bruce Olson Polaris

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Offline Up Late

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Re: Vintage Leasons Re-learned
« Reply #12 on: February 11, 2011, 11:47:41 AM »
I don't see a Yamaha winning a single I-500. 

Snowmobile racing isn't their strong suit.
Current Sleds in Stock: None. SOLD OUT!